The present invention relates to a reconstitutable composition comprising at least one alginate, an aqueous diet preparation comprising said composition and the use of the aqueous diet preparation for the treatment and/or prevention of overweight for both therapeutic and non-therapeutic purposes.
The number of people affected by overweight and obesity continues to rise along with the prevalence of comorbidity diseases that result from this condition.
However, the effective treatment of obesity remains a largely unachieved goal. Many studies indicate that the main causes of obesity are bad nutrition and lack of physical activity. Therefore, in order to prevent obesity it is necessary for people to change both their eating behaviors, to achieve a desired change in body weight, and include physical activity in their lifestyles.
In order to achieve a weight loss in relation to a diet plan, the main objective is to reduce the caloric intake on a daily basis, however, in order for an individual to be able to follow a diet, it is important that the individual does not feel hunger nor the complications normally associated with hunger, e.g. faintness. In this respect, foods containing strong-gelling fibers may provide a safe and efficacious strategy for reducing food and thereby caloric intake by stimulating the endogenous satiety signaling. Presently, one of the most promising fibers for this purpose is alginate.
Alginate is a non-digestible polysaccharide and can as such be classified as a dietary fiber. Dietary fibers have a range of physiological benefits and studies have shown that dietary alginates exhibit many of these. There is an improvement in GI barrier function and a reduction in the damaging potential of the luminal contents with changes in the colonic microflora. Dietary alginates reduce intestinal nutrient absorption and promote satiety both of which have implications for the control of Type II diabetes and obesity. (Brownlee et al., 2005 I. A. Brownlee, A. Allen, J. P. Pearson, P. W. Dettmar, M. E. Havler and M. R. Atherton et al., Alginate as a source of dietary fiber, Critical Reviews in Food Science and Nutrition 45 (6) (2005), pp. 497-510. View Record in Scopus/Cited By in Scopus (28).
Alginates have a wide range of uses, reflecting the diverse heterogeneous nature of these naturally-occurring polymers. They are widely used in the food and textile industries as thickeners, stabilizers, gel-formers, film-formers etc. Alginates, which have GRAS status (General Recognised As Safe) also have a wide range of uses in the pharmaceutical, healthcare and dental arena (Onsoyen, 1996 E. Onsoyen, Commercial applications of alginates, Carbohydrates in Europe 14 (1996), pp. 26-31).
Recently, the role of alginates in pharmaceutical and food applications, and in relation to human health has broadened recently with the recognition that they have a number of potentially beneficial physiologically effects in the gastrointestinal tract.
These include an effect on intestinal absorption and colonic health. Importantly, alginates have also been shown to moderate human appetite and energy intake.
The formation of alginate gels can either be obtained due to the presence of multivalent cations e.g. in the form of calcium (ionic gelation) or alternatively be obtained when the pH is less than 3.5 (acid gelation). It has been proposed that, following ingestion, ionic gelation of alginate in stomach acid, i.e. gelation in the presences of cations, can modulate feeding behavior through slowed gastric clearance, promoting a feeling of endogenous satiety by stimulation of gastric stretch receptors and attenuated nutrient uptake.
A number of documents describe food products comprising alginates, which undergo ionic gelation in the stomach and thereby produce a feeling of satiety.
One example of such a food product is known from WO 2003/053169. Said document discloses a liquid edible composition containing pectin or alginate together with a calcium salt which is insoluble at neutral pH. The calcium salt will dissolve in the stomach under the influence of the pH reduction. The increasing calcium concentration will stimulate the pectin and/or alginate gel-formation as calcium ions and the polysaccharides form a rigid matrix.
Similar, WO 2005/020717 and WO 2005/020719 relate to a food product, which in addition to alginate and insoluble calcium salt also comprises protein. The food product may be a liquid or a spoonable edible product.
Calcium-induced gel-formation requires that a high amount of calcium salt must be present in the product before consumption. In the drinks known from to US 2004/0228903, WO 2005/020717, WO 2005/020719 and US 2010/0260904 the calcium salt is present as an insoluble or otherwise protected salt, i.e. a salt that first becomes soluble when a pH value corresponding to the pH-value in the stomach has been reached.
The application, WO 2008/098579 relates to shelf-stable satiety enhancing liquid compositions comprising an alginate. Said liquid composition will upon ingestion, gel in the strongly acidic environment that prevails in the stomach. WO 2008/098579 discloses that the preferred gel-formation is obtained without the use of calcium ions. Furthermore, if calcium ions are present, only calcium salts, which are insoluble at neutral pH values, are contemplated.
The inventors have now discovered that a gel obtained without the use of calcium ions are not sufficiently strong to be able to be maintained in the stomach for a sufficiently long duration of time to provide the desired degree of satiety.
Furthermore, it is well-known that in order for an aqueous preparation to meet the acceptance of a general consumer the aqueous preparation shall not only have an agreeable appearance, e.g. have a low viscosity, be clear and without sedimentation and lumps but also have a pleasant smell and taste.
Alginates are conventionally associated with a fishy smell and odor coming from the seaweed from which they are extracted, and all the known aqueous preparations have to contain a number of flavor additives in order to conceal the unpleasant organoleptic properties of the alginates. However, addition of flavor additives are not always desirable, as said additives often have a negative impact on the viscosity of the aqueous preparation, i.e. the viscosity becomes too high before the preparation has been consumed.
A further problem with the prior art aqueous preparations is that the insoluble calcium salts present in such a preparation will precipitate and/or dissolve during storage resulting in the preparation having an unpleasant appearance.
Apart from the inconvenience of shaking the drink before consumption a heterogeneous product furthermore has the disadvantage that the consumer may either not obtain the calcium salt in a proper dose for an optimal gel formation to take place, or if the gel strength is insufficient the physiological stimulation of a feeling of satiety may not be obtained. Furthermore, the calcium salt will initiate the gel formation before consumption resulting in an unacceptable high viscosity.
The quantity of the soluble alginates, which will dissolve in water, is considered to be limited by the physical nature of the solutions rather than the actual solubility. As the concentration of alginate increases the solution passes through stages from a viscous liquid to a thick paste; at which point it becomes very difficult to disperse further alginate successfully. This is a well-known problem; see e.g. WO 03/053169, which discloses that it is not possible to add high concentrations of alginates to aqueous preparations, as the beverage will reach an unacceptable high viscosity before consumption.
As described above, alginates have been used to prepare several different compositions to modulate appetite and energy intake. However, these documents are all describing alginate formulations that undergo ionic gelation upon reaction with gastric acid as they are using an acid-soluble calcium source to form the desired alginate gel, and in the presence of divalent cations such as calcium ions, it has conventionally not been possible to ensure a stable aqueous solution having a consisting low viscosity before consumption.
This is due to the fact that the guluronic segments of alginate chains are able to adopt the form of a buckled ribbon, and these segments can associate with the calcium ions to form aggregates similar to an “egg-box”. Within these junction zones the alginate chains are in a regular pleated structure, which is stabilized by the calcium ions, each neutralizing a negative charge on two different chains. As a result, alginates richer in these guluronic blocks form stronger gels.
One solution to this problem could be to use alginates having a few guluronic segments, however, this will also provide weaker gels in the stomach with the result that the desired feeling of satiety cannot be obtained and maintained for a sufficient long period of time.
An additional problem when making aqueous preparations containing alginates is to obtain a solution, which is homogeneous and has a pleasant appearance; otherwise the consumer will not consider such a solution acceptable for consumption.
One of the problems with obtaining a homogenous solution and at the same time maintaining a low viscosity of the product before consumption is the hydrophilic nature of the alginates, which conventionally makes them useful as thickening agents, but leads to a number of difficulties when the alginates are to be dissolved in water.
When an alginate is dissolved in an aqueous preparation, the acid groups of the alginate are ionized and a viscous solution is obtained. With high viscosity and shear-thinning properties, its rheology is typical of solutions of flexible coil macromolecules. These two properties are proportional to the concentration and the molecular weight of the alginates. As the temperature rises, the viscosity decreases. This is reversible. Furthermore, when the alginates are solubilised, the alginates negatively charged carboxyl groups cause the straight alginate chains to repel each other and results in a stable aqueous solution. Such aqueous solution has smooth long-flow properties with Newtonian behavior.
Furthermore, even though alginates generally are considered to be soluble in water, a poor dispersion in water will occur if an alginate is added too rapidly to the water, i.e. producing pasty, floury lumps wetted on the outside, only. Thus, when an aqueous preparation is reconstituted from a powder, as suggested in WO 2003/053169, said preparation can only be prepared after a high-shear mixing for a relatively long duration, e.g. by blending the mixture for more than 30 minutes. The purpose of high-shear mixing is to prevent the particles to clump together, and become tacky as soon as the surface is hydrated. Powdered alginate is slowly poured into the upper part of a vortex created in the water by high-speed blender, which preferably must remain submerged to avoid too much aeration. If clumps form, the shear is often not sufficient to break them up. This is due to the tendency of the individual alginate particles in the powder to undergo surface swelling, i.e. they will stick to each other forming small aggregates of the partially swollen granules, generally with air trapped inside. Such aggregates, or “lumps,” are very difficult to disperse because the entrapped bubbles resist the penetration of water, and therefore, it is difficult for water to penetrate into the interior of a lumpy aggregate.
Use of coarse particles can be preferred in order to circumvent these problems, because they are easier to disperse and keep separate, however, such particles will be slower to dissolve compared to smaller particles, which will dissolve more rapidly. However, as mentioned above there is a substantial risk of the smaller particles to clump together and thereby preventing efficient solution and dispensation.
Accordingly when alginates in dietary products have been added to aqueous products as dry powders, it is very difficult to dissolve the alginates in water, and it has been proven to be a time-consuming task requiring excessive mixing.
Thus there is a demand for an aqueous diet product, which can be prepared in an easy, simple and reliable manner from e.g. a powder without requiring vigorous mixing, and at the same time ensuring that the final product meets the consumer's demands to organoleptic properties, i.e. the aqueous preparation must be homogenous, clear and have an acceptable low viscosity.